Device and method for the non-destructive magnetic testing of a wire rope

Abstract

The invention relates to a device (10) and a method for the non-destructive magnetic testing of a wire rope (11) with at least two twisted wire strands (12). The device (10) comprises a magnet assembly (20), a sensor assembly (24), and an evaluation unit (27). The magnet assembly (20) is configured to generate a magnetic field (23) along the wire rope (11). The sensor assembly (24) is arranged within the magnetic field (23) and includes a plurality of magnetic field sensors (25) arranged along a line (26) that circumferentially (45) encircles the wire rope (11). The evaluation unit (27) is configured to correlate the measurement data (28) of the magnetic field sensors (25) with a predetermined reference signal (30) to determine defects (32) and / or a lay length (31).By correlating the measurement data (28) with the comparison signal (30) in the circumferential direction (45), it is possible to determine errors (32) and / or the lay length (31) of the individual wire strands (12) particularly quickly, especially in real time.

Description

[0001] The invention generally relates to testing devices and testing methods for the non-destructive, magnetic testing of wire ropes.

[0002] Devices for the magnetic detection of defects, such as wire breaks, in wire ropes are generally known from the prior art.

[0003] JP 09-210968 A describes a device for magnetically and non-destructively inspecting a wire rope for breaks. For this purpose, a section of the wire rope is magnetically saturated by two magnetic poles. The magnetic leakage flux is measured using a detection coil. In a wire rope section that exhibits damage, for example, due to a wire break, the measured leakage flux deviates from the leakage flux measured in the other wire rope sections.

[0004] CN 112902821 A describes a device for determining an effective lay length function. The test device described therein has a multitude of magnetic field sensors that serve to detect the magnetic stray signal and to calculate the effective lay length function from the magnetic stray signal of the wire rope. A Fourier transform-based approach, a so-called multi-dimensional variable mode decomposition approach, is used to calculate the effective lay length function. This approach can be considered very computationally intensive, which can lead to resolution problems in practice.

[0005] CN 114538287 A describes a device and a method in which the velocity and displacement of a moving wire rope are determined from the texture of the magnetic flux using a sensor array. The measurement signals from the magnetic field sensors arranged on the wire rope are preprocessed by interpolation and noise reduction and then displayed as a grayscale image. Edges are found in the grayscale image using the Canny algorithm. The angle of the strands is then determined from the edges using the Hough transform. With this angle and a known lay length, the velocity of the wire rope can then be calculated.

[0006] CN 108333252 A describes a sensor arrangement in which two axially spaced rings of magnetic field sensors are used to test a wire rope. The distance between the two sensor rings is chosen to correspond to the lay length of the wire rope.

[0007] Finally, KR 10-1973067 B1 describes a device that determines the lay length of a wire rope, but with a magnetic sensor element integrated into the wire rope.

[0008] Based on this, the object of the invention is to provide an improved device and an improved method for the non-destructive magnetic testing of a wire rope, which in particular enables fast and easy processing of the sensor signals.

[0009] This problem is solved with the device according to claim 1 and the method according to claim 15:

[0010] The device according to the invention for the non-destructive, magnetic testing of a wire rope with at least two twisted (laid) wire strands is particularly suitable for mounting on an axial section of the wire rope and being movable relative to the wire rope. Conversely, the wire rope can also be movable relative to the device. The device comprises a magnetic unit, a sensor unit, and an evaluation unit.

[0011] The magnetic device comprises a first magnetic pole and a second magnetic pole axially offset from the first, between which a magnetic field is generated along the wire rope. The sensor device, with a plurality of magnetic field sensors arranged on a line circumferentially encircling the wire rope, is located between the magnetic poles.

[0012] The evaluation unit is designed to receive and process the measurement data from the magnetic field sensors. It is also designed to correlate this data with a predefined reference signal to determine defects and / or lay lengths. This correlation enables particularly fast signal processing and determination of defects and / or lay lengths in the wire strands. Signal processing can thus be performed very quickly, especially in real time. Circumferential correlation along the longitudinal direction of the wire rope allows for a complete inspection of the individual wire strands for defects and the determination of their lay lengths.

[0013] A special feature of the device according to the invention is that the particularly fast processing of the measurement data enables non-destructive magnetic testing of the wire rope, even at high relative speeds of the wire rope to the device and vice versa. This allows the lay length and / or defects to be determined, especially during operation. By comparing the lay length with reference values ​​and / or the lay lengths of the individual wire strands to each other, characteristics such as changes in lay length can be detected. These can serve as early indicators of wear, overloading of the wire rope, and the like, which can lead to wire breaks or elongation of the wire rope.

[0014] The predetermined comparison signal of the evaluation device is specifically designed as a rectangular function, which makes the calculation of the correlation signal as simple as possible and feasible using computationally efficient steps.

[0015] Preferably, the correlation signal values ​​range between -1 and +1. A correlation signal of 0 indicates that there is no correlation between the measured data and the reference signal. Conversely, a correlation signal of -1 indicates that the reference signal and the measured data are 180° out of phase with each other. A correlation signal of +1 indicates that the measured data (completely) match the reference signal. The evaluation unit may include a correlation module designed to perform the correlation between the measured signals and the reference signal. The correlation module may be implemented as a hardware or software module.

[0016] The evaluation unit may also include a lay length module, a wire break detection module, and / or an imaging module, which may be configured to further process the correlation signal. These additional modules may also be implemented as hardware or software modules. The lay length module may be configured to determine the lay length of each wire strand. The wire break detection module may be configured to detect individual wire strand defects. The imaging module may be configured to assemble a three-dimensional image, a so-called heatmap, which displays the correlation signal in the longitudinal and circumferential directions of the wire rope.

[0017] The evaluation unit is specifically designed to convolve the measurement data from the magnetic field sensors with the reference signal along the circumference. The correlation module can then be implemented as a convolution module.

[0018] The device can, in particular, include a length measuring device configured to determine the relative path length between the sensor device and the wire rope, thereby enabling the determination of an absolute measure of the lay length. Furthermore, the device allows for the precise determination of the position of the measured errors in the circumferential and longitudinal directions. The length measuring device can, for example, include a measuring wheel with an encoder, which is held (pre-tensioned) against the wire rope such that the measuring wheel rolls along the wire rope during any relative movement between the device and the wire rope. The relative path length between the device and the wire rope can be measured using the encoder.

[0019] The evaluation unit is preferably configured to post-process the correlation signal using a regression parabola, in particular a cubic regression parabola. The evaluation unit may include a post-processing module configured for post-processing the correlation signal with the regression parabola. The post-processing module may be implemented as a hardware or software module.

[0020] In one embodiment, the evaluation device is equipped with an analog signal processing module configured to convolve the measurement data from the magnetic field sensors along the circumference with the reference signal. This analog convolution of the analog measurement data enables particularly fast signal processing. Preferably, the analog output signal of the analog signal processing module is converted into a digital output signal by means of an analog-to-digital converter.

[0021] In an alternative embodiment, the measurement data from the individual magnetic field sensors are converted into digital measurement signals using an analog-to-digital converter. In this embodiment, the evaluation unit includes a digital signal processing module configured to convolve the comparison signal along the circumference with the digitized measurement data from the magnetic field sensors. The digital signal processing module can be, for example, a digital signal processor (DSP), a field-programmable gate array (FPGA), or the like.

[0022] Regardless of the embodiment, the evaluation device is preferably configured to display the correlation signal with spatial resolution in the circumferential and longitudinal directions of the wire rope.

[0023] Furthermore, the evaluation unit can be configured to determine a centering measure from the correlation signal, which indicates the radial position of the wire signal within the sensor device. The evaluation unit can, for example, include a centering measure module designed to determine the centering measure from the correlation signal. The centering measure can be used, in particular, to eliminate false positive wire fault detections.

[0024] It is preferred that the comparison signal be adaptable to the number of strands in the wire rope.

[0025] Preferably, the evaluation device is also configured to calculate the cross-correlation between the comparison signal and the measurement data of the magnetic field sensors along the circumference.

[0026] The object of the invention is further achieved by the inventive method for the non-destructive magnetic testing of a wire rope with at least two twisted (laid) wire strands. The inventive method comprises the following steps: - Arranging the device of the above type, movable relative to the wire rope on an axial section of the wire rope; - Formation of a magnetic field in the axial section along the wire rope; - Measuring the magnetic field along a line encircling the wire rope; and - Evaluation of the measurement data of the magnetic field to determine the error and / or lay length of the wire rope by correlation with a predetermined reference signal.

[0027] The features and advantages described with regard to the device according to the invention, in particular with regard to the evaluation unit, are also applicable to the method according to the invention.

[0028] Further details of advantageous embodiments or specific aspects of the invention will become apparent from the drawings, the description, and the dependent claims. These show: Fig. 1 A perspective view of the device for non-destructive magnetic testing of a wire rope; Fig. 2 A longitudinal section of the device made of Fig. 1; Fig. 3 A cross-section through the device and the wire rope; Fig. 4 A schematic representation of the evaluated wire rope; Fig. 5 An example of the procedure; as well as Fig. 6 Another example of the process according to the invention.

[0029] In Fig. Figure 1 shows an example of a device 10 for non-destructive magnetic testing of a wire rope 11.

[0030] The wire rope 11 is a metal rope with several twisted wire strands 12. The wire strands 12 have a multitude of wires 44 made of a metal, e.g. steel, which are twisted (blown) together to form the respective wire strand 12.

[0031] The device 10 is arranged on an axial section 13 of the wire rope and is movable relative to the wire rope 11 in the longitudinal direction 14 and vice versa, the wire rope 11 is movable relative to the device 10.

[0032] The transverse direction 15 of the wire rope 11 extends orthogonally to the longitudinal direction 14, preferably radially to the wire rope 11.

[0033] In Fig. 1. The wire rope 11 is movably arranged relative to the device 10. The direction of movement 16 is in Fig. 1 represented by the arrows. Unlike in Fig. As shown in Figure 1, the wire rope 11 can also remain stationary while the device 10 moves relative to the wire rope 11. Furthermore, a superposition of the movement of the wire rope 11 and the moving device 10 is also possible.

[0034] Regardless of whether the wire rope 11 moves relative to the device 10 and / or vice versa, the device 10 can have a length measuring device 17 which is configured to determine the relative path length 55 between the device 10 and the wire rope 11.

[0035] In Fig. In the figure 1, the length measuring device 17 is designed as a measuring wheel which has a rotatably mounted wheel 18 that is mounted on the wire rope 11 such that, during a relative movement between the wire rope 11 and the device 10, the wheel 18 rolls along the circumference of the wire rope 11. For this purpose, the length measuring device 17 has an encoder 19 which converts the angular signal into a length signal.

[0036] The device 10 comprises a magnetic assembly 20 with a first magnetic pole 21 and a second magnetic pole 22 axially spaced from the first magnetic pole 21, between which a magnetic field 23 is formed. The magnetic field 23 is formed in the longitudinal direction 14 of the wire rope 11.

[0037] A sensor device 24 with a plurality of magnetic field sensors 25 is arranged between the two magnetic poles 21 and 22. The magnetic field sensors 25 are arranged on a line 26 that wraps around the wire rope 11 in a circumferential direction 45.

[0038] The device 10 also includes an evaluation unit 27, which is configured to receive and process measurement data 28 from the magnetic field sensors 25 of the sensor device 24. The evaluation unit 27 is specifically configured to correlate the measurement data 28 with a predetermined reference signal 29 and to evaluate the resulting correlation signal 30 with respect to the lay length 31 of the wire rope 11. The evaluation unit 27 can also be configured to detect strand defects 32 in the correlation signal 30. The details of the signal processing of the evaluation unit are explained in more detail below.

[0039] The device 10 has a housing 33. The housing 33 is located in the Fig. The example shown in Figure 1 is constructed in multiple parts. It has an upper shell 34 and a lower shell 35, which are attached to each other in a way that allows them to be opened. The magnetic device 20 and the sensor device 24 can also be constructed in multiple parts, such that they have an upper part and a lower part, which can be opened and closed together with the upper shell 34 and the lower shell 35 of the housing 33, respectively. A guide channel is provided in the housing 33, in which the wire rope 11 is guided during the measurement.

[0040] The in Fig. The device 10 shown also has a communication interface 36 which makes it possible to send the correlation signal 30, the determined beat length 31 and / or determined strand faults 32 to a user terminal device 37 or any other computer, server or cloud.

[0041] The device 10 can also include a storage device 38, which can be configured to temporarily store measurement data 28, comparison signals 29, correlation signals 30, detected lay lengths 31, or detected strand faults 32. The evaluation device 27 can be connected to the communication interface 36 and the storage device 38.

[0042] Fig. Figure 2 shows a longitudinal section through an example of the magnetic device 20. The magnetic device 20 is arranged along an axial section 13. The magnetic device 20 has a first magnetic pole 21 and a second magnetic pole 22, between which a magnetic field 23 is formed.

[0043] The magnetic field 23 is aligned in the longitudinal direction 14 of the wire rope 11. The first magnetic pole 21 and the second magnetic pole 22 are connected by a yoke 39. The first magnetic pole 21 is arranged at a first axial position 40, and the second magnetic pole 22 is arranged at a second axial position 41. The sensor device 24 is arranged at a third axial position 42 between the first axial position 40 and the second axial position 41. The third axial position 42 is located between the first axial position 40 and the second axial position 41.

[0044] The sensor device 24 comprises a plurality of magnetic field sensors 25 arranged on a line 26 enclosing the wire rope 11. The magnetic field sensors 25 are preferably arranged equidistant from one another on the line 26. The line 26 can be a circle encircling the wire rope 11.

[0045] In Fig. Figure 3 shows a cross-section through the sensor device 24 with a wire rope 11 arranged therein. The wire rope 11 has several twisted (laid) wire strands 12 arranged in multiple layers around a core 43. Each of the wire strands 12 consists of individual wires 44. The in Fig. The sensor device 24 shown in Figure 3 has a two-part structure. It has an upper and a lower part.

[0046] Fig. Figure 4 shows a detailed view of a wire rope. Fig. Figure 4 also shows the lay length 31 of the wire strands 12. The lay length 31 of a wire strand is understood to be the pitch of the helically laid wire strands 12. In multi-layer wire ropes, the wire strands of two successive wire layers usually have different lay lengths but often the same lay angle 52.

[0047] Fig. Figure 5 shows an example of signal processing. The measurement data 28 from the sensor device 24 and the relative path length 55 from the length measuring device 17 are sent to the evaluation device 27.

[0048] The sensor unit 24 Fig. In this example, component 2 features a multitude of analog-to-digital converters that convert the measurement signals from the individual magnetic field sensors 25 into digital measurement data 28, representing magnetic field measurement points along the circumference of the wire rope 11. In a processing module 46, the measurement data 28 from the individual magnetic field sensors 25 are further processed such that the measured values ​​are arranged sequentially in the circumferential direction 45. The relative path length 55 allows the measured values ​​to be assigned an axial position. The processed measurement data 54 are thus arranged in the circumferential direction 45 and the longitudinal direction 14.

[0049] The processed measurement data from the processing module 46 are correlated in a correlation module 47 with the reference signal 29 in the circumferential direction 45. The reference signal 29 can be a square wave. A correlation signal 30 is thus generated in the correlation module 47. The correlation signal 30 can then be further processed in a lay length module 48, a wire break detection module 49, and / or an imaging module 50.

[0050] The lay length module 48 is designed to determine the lay length 31 of each wire strand 12. The wire break detection module 49 is designed to detect individual wire strand defects. The imaging module 50 is designed to assemble a three-dimensional Fig. , a so-called heatmap. The three-dimensional Fig. The correlation signal 30 shows the longitudinal direction 14 and circumferential direction 45 of the wire rope 11.

[0051] Fig. Figure 6 shows another example of signal processing. For the one in Fig. The example of signal processing shown in section 6, as described above, applies to... Fig. 5 said accordingly. The signal processing in Fig. 6 differs from signal processing in Fig. 5 by the fact that the correlation module 47 in Fig. 6 is an analog correlation module. The digital conversion by the analog-to-digital converter 53 takes place in Fig. 53 after the correlation module 47.

[0052] The invention relates to a device 10 and a method for the non-destructive magnetic testing of a wire rope 11 with at least two twisted wire strands 12. The device 10 comprises a magnet assembly 20, a sensor assembly 24, and an evaluation unit 27. The magnet assembly 20 is configured to generate a magnetic field 23 along the wire rope 11. Within the magnetic field 23, the sensor assembly 24 is arranged with a plurality of magnetic field sensors 25, which are positioned along a line 26 encircling the wire rope 11 in the circumferential direction 45. The evaluation unit 27 is configured to correlate the measurement data 28 of the magnetic field sensors 25 with a predetermined reference signal 30 to determine defects 32 and / or a lay length 31.By correlating the measurement data 28 with the comparison signal 30 in the circumferential direction 45, it is possible to determine errors 32 and / or the lay length 31 of the individual wire strands 12 particularly quickly, especially in real time. Reference symbol: 10 Device for non-destructive magnetic testing 11 Wire rope 12 strands of wire 13 Axial section 14 Longitudinal direction of the wire rope 15 Transverse direction of the wire rope 16 Direction of movement 17 Length measuring device 18-inch wheel 19 encoders 20 Magnetic device 21 first magnetic pole 22 second magnetic pole 23 Magnetic field 24 Sensor system 25 magnetic field sensors 26 encircling line 27 Evaluation unit 28 (unprocessed) measurement data 29 Comparison signal 30 Correlation signal 31 stroke length 32 strand faults 33 cases 34 Upper shell of the case 35 Lower shell of the housing 36 Communication interface 37 User terminal 38 Storage device 39 yoke 40 first axial position 41 second axial position 42 third axial position 43 deposit 44 wire 45 Circumferential direction 46 Processing module 47 Correlation module 48 stroke length module 49 Wire break detection module 50 Imaging module 51 3D data illustration 52 impact angles 53 Analog-to-Digital Converters 54 (processed) measurement data 55 relative path length QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 09-210968 A

[0003] CN 112902821 A

[0004] CN 114538287 A

[0005] CN 108333252 A

[0006] KR 10-1973067 B1

[0007]

Claims

[1] Device (10) for non-destructive magnetic testing of a wire rope (11) with at least two twisted wire strands (12) which can be arranged on an axial section (13) of the wire rope (11) and are movable relative to the wire rope (11) in the longitudinal direction (14) or conversely, the wire rope (11) is movable, comprising: - a magnetic device (20) with a first magnetic pole (21) and a second magnetic pole (22) axially spaced from the first magnetic pole (21), between which a magnetic field (23) is formed; - a sensor device (24) arranged between the magnetic poles (21, 22) with a plurality of magnetic field sensors (25) arranged on a line (26) encircling the wire rope (11) in the circumferential direction (45); and - an evaluation device (27) which is configured to receive and process the measurement data (28) of the magnetic field sensors (25) of the sensor device (24), wherein the evaluation device (27) is configured to correlate the measurement data (28) with a predetermined comparison signal (29) and to evaluate the resulting correlation signal (30) with respect to the stroke length (31) and / or error (32). [2] Device (10) according to claim 1, characterized by , that the comparison signal (29) is designed as a rectangular function. [3] Device (10) according to claim 1 or 2, characterized by , that the values ​​of the correlation signal (30) lie between -1 and 1. [4] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) is configured to convolve the comparison signal (29) along the circumference with the measurement data from the magnetic field sensors (25). [5] Device (10) according to any one of the preceding claims, further characterized by a length measuring device (17) which is set up to determine the relative path length (55) between the device (11) and the wire rope (11). [6] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) is set up to process the correlation signal (29) using a regression parabola, in particular a cubic regression parabola. [7] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) has an analog signal processing module which is configured to convolve the comparison signal (29) along the circumference with the measurement data (28) of the magnetic field sensors (25). [8] Device (10) according to claim 7, characterized by, that the analog output signal of the analog signal processing module is converted into a digital output signal by means of an analog-to-digital converter. [9] Device (10) according to any one of claims 1 to 6, characterized by , that the measurement data (28) of the individual magnetic field sensors (25) are converted into digital measurement signals using analog-to-digital converters. [10] Device (10) according to claim 8, characterized by , that the evaluation device () has a digital signal processing module which is configured to convolve the comparison signal (29) along the circumference with the digitized measurement data of the magnetic field sensors (25). [11] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) is set up to display the correlation signal (30) spatially resolved in the circumferential and longitudinal directions (14, 15) of the wire rope (11). [12] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) is configured to determine a centering dimension that specifies the radial position of the wire rope (11) within the sensor device (24). [13] Device (10) according to any of the preceding claims, characterized by , that the comparison signal (29) can be adapted to the number of strands of the wire rope (11). [14] Device (10) according to any of the preceding claims, characterized by , that the evaluation device (27) is set up to calculate the cross-correlation between the comparison signal (29) and the measurement data (28) of the magnetic field sensors (25) along the circumference. [15] Method for non-destructive magnetic testing of a wire rope (11) having at least two twisted wire strands (12), comprising: - Arranging the device (10) according to one of the preceding claims movable relative to the wire rope (11) on an axial section (13) of the wire rope (11); - Forming a magnetic field (23) in the axial section (13) along the wire rope (11); - Detection of the magnetic field (23) on a line (26) encircling the wire rope (11) in a circumferential direction (45); and - Evaluation of the measurement data (28) of the magnetic field (23) to determine the error and / or lay length of the wire rope (11) by correlation with a predetermined reference signal (29).

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